DE1291757C2 - Rotary tube for heating or cooling pourable or liquid goods - Google Patents

Description

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The invention relates to a rotary tube for heating or cooling pourable or liquid goods, in particular for burning alumina, in which the helical, at regular angular intervals internally offset internals are provided which protrude from the pipe wall inwards and are bounded inside by an imaginary cylinder coaxial with the rotary tube.

In the case of a rotary tube with a horizontal or slightly inclined axis that rotates around its axis and at one end with a non-gaseous material, for example a liquid or a Bulk material or heap is charged, which leaves the rotary kiln at its other end, is the " The size of the cross-section of the stream, commonly referred to as the bed, of the stream traveling through the rotary tube Good essentially depends on the speed of rotation and the cross-section of the Rotary barrel as well as the properties of the good, the most important of which is its angle of repose or internal Angle of friction is.

If you want to increase the cross-section of the bed regardless of the parameters mentioned, to For example, the dwell time of the goods in the rotary kiln or the heat exchange between the goods and changing a gas flowing through the free part of the rotary tube is usually seen one or more rings coaxial with the rotary tube, the inner diameter of which is smaller than that of the rotary kiln. Such rings are usually referred to as storage rings.

Known storage rings consist of a flat, annular plate. The arrangement of such Staurings in a rotary tube has the disadvantage that the cross section, which for with or against the migrating material flowing gases remains free, is greatly reduced

decreases the passage cross-dam ring known design of the

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querschmttes w "* = ^ ™ _{that the} baffle ring Zentri *? f £ ^ve ™ ß _ett 'appear from 100 to angle untei ™ _{right Wink6l} ^m = ₉₀ A _1, ^ J £ 33 or loj"
= If ⁰ Neugradjv ^^ ^ ^ ^ ^

The ^btroi °! R? _h ° in relation to the flow rate in the _umge ™ characteristic

^^^ SL ^ dJ Se have a consequence that beundJurimlenz the ^ _{liqi G}

Trachthche quantities aes i ^ i
send along d
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schnebenen genus ^

smd die? <~ ^ndeU ° ™ ^g : l - _{! nander}
Axial compressor as ^ J ^
slightly overlapping

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depending on theirs

Built-in components are therefore insoluble with their driving effect linked, if one disregards the exception that the internals are sealingly joined together thus form an ordinary storage ring.

Another known rotary tube (German patent specification 272 253), which is provided as a mixing drum, has a Mtz: ν l formed screw-like blades or vol-spirals at each of its two ends, while only small screw segments are arranged in the middle area of the Du 1 tube . are angeomnet apart a distance such that d? ~ can pass stromen mix between the einzehien screw flights The VoIlspiralen and screw segments smd one side of the central cross section plane of the rotating tube aut right-handed and formed on the other beite luiKsgangig. The rotary tube can optionally be fed with the material to be mixed from one end or from both ends, while it is rotated in such a way that the material to be mixed is conveyed to the center of the rotary tube and mixed there. The material to be mixed accumulates in the middle of the rotary tube in such a way that only a small residual cross-section remains free. After the end of the mixing process, the material to be mixed - inevitably at both ends of the rotary tube at the same time - is discharged in that the direction of rotation is reversed.

The invention is based on the object of providing a rotary tube of the type described at the beginning to design that with a given internal cross-section of the rotary kiln and a jam of a given cross-section, So even with a given free surface area of the goods, the free passage cross-section for em Gaseous or vaporous medium to be passed through the rotary tube above the accumulation, if possible large, so is limited by the internals to the lowest possible extent.

This object is achieved according to the invention in that the helical internals are one of the Direction of rotation of the rotary tube have opposite slope and each other in an angular range overlap that with the central angle

a chord of the cross section of the rotary tube tangent to the imaginary inner limiting cylinder matches

In contrast to the above-known generic rotary kiln can in inventiveness x, modern rotary tube contained schiittfähige or liquid material to overcome the obstacle formed by the wendelfönnigen fixtures only when it has become so highly congested that it is the lowest over the top of each Built-in can flow away. The internals designed according to the invention accordingly have the same static, that is to say also effective, damming effect when the rotary kiln is at a standstill as the usual self-contained damming rings; the flow resistance of the internals according to the invention% s for a gaseous or vaporous medium to be passed through the rotary tube above the dam is, however, very much lower than the flow resistance of self-contained dam rings, since the medium can flow through between the individual internals according to the invention.

The helical fittings can - as is generally the case - at the front and rear a plane containing the axis of the rotary tube may be limited. The flow resistance for the »5 Gaseous or vaporous medium passed through the rotary tube and at the same time that for the Production of the internals required material costs are particularly low if according to a development of the invention, each of the helical internals from and behind by one each the plane tangent to the inner limiting cylinder is limited.

The possible uses of the rotary kiln according to the invention are numerous and include all heat exchangers for direct heat exchange between a steam or gas, for example Flue gas, on the one hand, and a liquid or bulk material on the other hand, indifferent, in which direction the heat exchange takes place. Examples are the application as a rotary kiln for the burning of alumina and as a rotary tube cooler for burnt alumina.

The invention is illustrated schematically below with the aid of hand Drawings by comparing various known rotary tubes with several Embodiments of the rotary kiln according to the invention explained in more detail. It shows

F i g. 1 a known type of heat exchanger designed as a rotary tube in one to its axis vertical cut,

F i g. 2 another known type of heat exchanger designed as a rotary tube,

F i g. 3 a third known type of heat exchanger designed as a rotary tube,

F i g. 4 a heat exchanger designed as a rotary tube with features of the invention in one Section perpendicular to its axis of rotation,

F i g. FIG. 5 is an illustration that makes it easier to understand the mode of operation of the functions shown in FIG. 4 embodiment shown to facilitate the invention,

F i g. 6 shows a second embodiment of a rotary tube according to the invention in a vertical section to the axis,

F i g. 7 shows a detail from FIG. 6th

In all figures, parts that correspond to one another are provided with the same reference numerals.

The in F i g. The known heat exchanger shown in FIG. 1 comprises a tube 1 with a horizontal or slightly inclined axis which rotates about its axis 2 in the direction of arrow 10. The item 5 to be treated flows through the pipe 1 in the lower part of the cross section, while hot or cold gases flow through the pipe in the upper part of the cross section, depending on whether the item is to be heated or cooled. A sector 3 of the tube 1 bounded by two adjacent axial planes alternately passes through the area 4, where it absorbs or emits heat, and the lower area, where it emits the absorbed heat to the good 5 or absorbs new heat from the good. In practice, the heat-storing mass of the heat exchanger is increased by, as shown in FIG. 2 arranges concentric rings 6, 7 in the tube 1, which rings consist of several tires held in place by spokes 8.

Viewed from the axis 2 of the tube 1, the mass of the good 5 appears at an angle 9, which is referred to as the central angle. The amount of heat transferred to the good 5 with each revolution of the tube 1 depends on this central angle and reaches its maximum at a certain size of the central angle, which depends on the nature of the good. In the case of aluminum oxide A1 ₂ O _S , the optimum value is 135 "; however, the amount of heat transferred only decreases by 5% if the angle changes to 155 "or 100". With regard to the throughput, a central angle of 135 to 155 »is preferably maintained.

The plane delimiting the desired bed intersects the plane of FIG. 1 in a straight line, which surrounds a circle 11 drawn around the center point 2 when the pipe 1 rotates around its axis 2 turns.

According to FIG. 3, the central angle 9 is usually obtained by using a to the rotary tube coaxial, uninterrupted ring 12 which is delimited by the inner circle 11. At a central angle of 155e this ring leaves only a very small area on the order of one Twelfth of the total cross-section is free for smoke gases or gases to pass through. The this Passage cross-section inversely proportional speed of the gases is therefore large, so that a strong turbulence arises and large amounts of the good 5 are carried away, regardless of whether this is is liquid or solid.

According to the invention, this disadvantage is eliminated in that, as shown in FIG. 4 shown in A baffle ring is arranged on the flow path of the goods 5, which has several helical surfaces coaxial with the pipe 1 includes, which each have the same angle of revolution and at the same angle in the circumferential direction are offset from one another. The direction of rotation of the helical surfaces is opposite to the direction of rotation of the tube 1.

The helical surfaces are delimited by a cylindrical surface 11 coaxial with the rotary tube 1; the these Cylinder touching and the rotary tube intersecting plane 18-19 bounded together with the Rotary tube a cylinder segment occupied by the good 5, the cross-section of which is the largest possible Representing cross section of the bed.

If the central angle 9 has a value of A grad and if the retaining ring / 1 comprises helical flat threads, then give '

5 6

see the angle of revolution F of each thread turn from two straight lines that are also parallel to the surface lines

of formula 20 'and 20 ". Pie upstream weir

400 sending page appears in the upper part of the development.

F - - + A grad. Since _s j _c h the tube slowly rotates (arrow 10),

^ S fill the spaces between the spiral

Such an angle of rotation enables the entrances to a height that corresponds to the level of the current '

standing of a liquid jam with a centri 'upward liquid corresponds as soon as

angle A, in the case of a pourable material, which you get in connection with this liquid. As

The angle of repose is not negligibly small, as can be seen in the development of FIG

the angle of revolution can be smaller. ie the liquid that is in the spaces between the

According to FIG. 6, the helical surfaces can each have helical surfaces of the same level, always on one

be bounded by two levels, which the inner lock that binds the bed to it, to one level

Touch the cylinder 11 and drop one end each, which has a central angle of less

the helix included. as 155 «. As an example, the eye

The thread pitch can be viewed arbitrarily, in which the space 23 ',

However, it must not be too small, so that 22 ', 22, 23 become, as a result of the rotation, with liquid

di? through the spaces between the helix and the point 23 'lies on the straight line 19'.

Gases or smoke gases flowing through the surface. At this moment point 22 coincides with the

do not suffer excessive pressure loss; still straight lines 18 'together; that means that the

the pitch may be too great so that the thread at ap from the turning surface 22-22 '

the rotation of the ucs pipe still along the spiral path after the level of the liquid has been equalized

areas can migrate back. opposes the drainage of the liquid.

In the following, the mode of operation of the invented- This consideration makes it understandable that

proper stowage ring explained; at the end of the day, each thread turns from one

taken that the goods to be stowed are a liquid as a spiral surface sector with an angle of rotation of

and the rotary tube 1 has a horizontal axis. 400 _XT .,., _,. , ..,, ·.

However, this explanation also applies to the intestinal tract, if the ΊΓ ^New 8 ^wheel 8 ^{can both of them}

Well a pile is and / or the rotary tube is slightly attached to the ends of a gusset, which thereby

is inclined to the horizontal. arise that one can continue the spiral -

In the heat exchanger according to FIG. 4, a 30 surface with two planes intersects the inner

Jam, which in the example shown touch a centric cylinder and each have an end point of the

has an angle of 4 = 155 ⁸ , by η = 8 helix the helical surface generating helix on the.

get areas. The angle of rotation F of the helical rotary tube included.

surface area is: The angle of rotation of each of these gussets is therefore

³⁵ after-γ. Fig. 6 shows such a storage ring.

400 400 ~~

F = - + A = + 155 = 205 ". a comparison with Fig. 4 makes the importance of

ⁿ ° described limitation of the helical surfaces

lich. Fig. 7 represents a thread for a jam

To understand the operation of the is 40 of 155 "central angle. The thread comprises helical surface formed storage ring to facilitate a helical surface sector 31 with a circulation Tern, the arrangement shown in Fig. 4 in ^^ _{32,400 = d} ^ _{ckel 33}

Fig. 5 by means of the axis 2 and cut at right angles 8 '

The straight line projected onto the wall of the rotary tube 1 and 34 with a circumferential angle 35 of in each case and this projection is extended in the lower part of 45 jL ₌ ^ls -L = 77 5g, FIG. 5 angled in one plane. 22 '*

The individual spiral surfaces 21-28 appear in the case of the dam ring according to the invention, the diameter

the settlement as a straight line 21-21 'to 28-28', the lass cross-section for the gases or flue gases only in are inclined against the surface lines of the cylinder. reduced to the smallest possible extent Limits 18 and 19 of the jammed goods or 50 speaks the total cross section of the rotary kiln 1, the The beds appear as two to the surface lines of which is reduced by the cross-section of the bed Rotary tube 1 parallel straight lines 18 'and 19'. Let the passage cross-section is therefore much larger than Assume that the rotary tube is along the jacket the cross-section 4, which is coaxial to the rotary tube line 20 cut open, the development by ring 12 in F i g. 3 releases.

For this purpose 2 sheets of drawings

Claims (1)

1. Rotary tube for heating or cooling pourable or liquid goods, in particular for burning alumina, in which the helical, at regular angular intervals internally offset internals are provided which protrude from the pipe wall inwards and are delimited on the inside by an imaginary cylinder coaxial with the rotary tube, thereby characterized in that the helical internals (13; 14) have a direction of rotation of the rotary tube (1) opposite St «- have and overlap each other in an angular range that corresponds to the central angle <9) one of the imaginary inner limiting cylinder (11) the tangent chord (18-19) of the cross section of the rotary tube (1) ^ Rotary kiln according to claim 1, characterized